The Research In Supercapacitor Performance Of New Co,Ni Based CPs-derived Porous Materials

As a new type of energy storage device,supercapacitor has the advantages of excellent reversibility,high power density,high efficiency charge and discharge and long cycle life.The preparation of novel electrode materials with unconventional structure has always been a research hotspot in the field of supercapacitors.Porous coordination polymers（PCPs）are particularly suitable for the design and preparation of capacitive electrode materials due to the controllable porous structure and special electrochemical behavior of the derived materials.In this paper,the supercapacitor performance of new cobalt-based CPs derived Co₃O₄@C materials,new nickel-based CPs derived NiO and nitrogen-doped porous carbon materials will be studied in depth.1.One unusual coordination polymer[Co（bib）_1.5（NO₃）₂（CHCl₃）]_∞,named as CP-3-ZX,is assembled from ligand 1,4-bis（imidazol-1-yl）benzene（bib）and cobalt nitrate.In CP-3-ZX,the Co ^IIion is connected by bib into 1D double-track ladders,which are mutually packed to form tetragonal channels with the porosity of 23.9%.Following,CP-3-ZX is employed as a precursor,and a sequence of Co₃O₄@C composites with various carbon contents are obtained through changing the annealing temperature.A moderate amount of carbon can enlarge the Brunauer-Emmett-Teller（BET）specific surface area,enhance the conductivity,and finally augment the capacitance of carbonaceous material.The extensive comparison reveals Co₃O₄@C-400,designated by the calcined temperature of 400°C,has the highest specific capacitance of 317 F g^-1due to the optimized carbon content among these Co₃O₄@C composites.Moreover,an asymmetric supercapacitor Co₃O₄@C-400//AC is fabricated by using the positive electrode of Co₃O₄@C-400 and negative electrode of activated carbon（AC）.Co₃O₄@C-400//AC owns energy density of13.8 Wh kg^-1,and the retention of 82%after 5000 cycles indicates good cycling durability.Significantly,the 4×2 battery unit of Co₃O₄@C-400//AC can be utilized to run a time counter for 11 seconds or light a toy Christmas tree more than 20 minutes.Excellent performance indicates that Co₃O₄@C-400 has great application potential in the field of supercapacitors.2.Two high-performance electrode materials,NiO and nitrogen-doped porous carbon materials（NPCs）,were successfully prepared using coordination polymers（CP-4-ZX）{[Ni（bibp）₃]（Cl O₄）₂}_∞as precursors by changing the calcination conditions.At 0.5 A g^-1,the capacitance of NiO and NPCs electrode materials reaches 714 F g^-1and 200 F g^-1,respectively.An asymmetric supercapacitor（ASC）composed of NiO as a positive material and NPCs as a negative material has an excellent specific energy density of 32.2 Wh kg^-1at a power density of 400.6 W kg^-1.Long-term cycle test results show that ASC has good cycle stability.It is easy to spot light emitting diodes using the device,which demonstrates its applications.The device can easily light light-emitting diodes,demonstrating its practical application value.Therefore,CP-4-ZX is a good precursor for preparing capacitive electrode materials.